Preliminary studies suggest that by combining the high spatial resolution (millimeters) of functional magnetic resonance imaging (fMRI) with the high temporal resolution (milliseconds) of electroencephalography (EEG) it is possible to obtain noninvasive spatiotemporal maps of cerebral activitylntrinsic brain activity, such as cortical information exchange, changes in arousal and alertness, or epileptic spiking, is not amenable to precise reproducibility over time. Although separate measurements of fMRI and EEG are adequate for some situations, cognitive experiments involving learning or priming require concurrent measurements. We propose to use techniques we have been developing to build a medical device that will allow concurrent EEG and fMRI recordings to be obtained safely and accurately. Preliminary results show that the power dissipated by the MRI radio frequency (RF) fields in the subject's tissue greatly increases in the presence of EEG electrodes and leads. The proposed instrumentation will minimize the RF fields interaction to improve both subject safety and quality of the fMRI recordings. The proposed instrument will also include a new time varying adaptive noise cancellation scheme to reduce artifact noise present on the EEG. Instrumentation for concurrent EEG/fMRI will be tested using steady-state EEG, visual evoked potential (VEP), and event-related potential (ERP) experimental protocols. Event-related potentials (ERPs) are small phasic potentials elicited in conjunction with sensory, cognitive, and motor events that can be detected by recording from scalp electrodes. Although the amplitude and latency of various ERPs have been extensively studied with EEG, the location of the potential sources remains largely unknown. We propose a series of simultaneous fMRI/EEG experiments that will investigate the spatial location and temporal processing of event-related potentials in the human brain.